Multi-Speed OCT Swept Source with Dynamic K-Clock Sampling
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Solution Overview
Problem
Optical coherence tomography (OCT) systems with multi-sweep rate swept sources face challenges in adapting to different sweep rates optimally, leading to suboptimal performance due to fixed optical frequency sampling intervals, which results in lower performance compared to k-clock based systems.
Innovation Solution
An optical coherence tomography system that utilizes an optical swept source capable of frequency scanning at multiple sweep rates, with a k-clock module that generates and selects reference clock signals corresponding to different optical frequency sampling intervals, allowing the analog-to-digital converter to maintain a consistent sampling rate across varying sweep speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed optical frequency sampling interval is used in multi-sweep rate swept sources, then the system structure is simplified, but the imaging performance deteriorates due to suboptimal sampling at different sweep rates
Solution Approach 1:
The patent implements dynamic adjustment of the optical frequency sampling interval based on the swept source's sweep rate. The system automatically modifies the sampling interval to match the current sweep rate, ensuring optimal sampling conditions whether operating at high or low speeds. This dynamic adaptation resolves the contradiction by making the sampling interval flexible rather than fixed, maintaining high imaging performance across varying sweep rates without requiring complex hardware changes.
Solution Approach 2:
The patent changes the sampling parameter (optical frequency sampling interval) according to the sweep rate conditions. When the sweep rate changes, the system adjusts the sampling interval parameter accordingly - using smaller intervals at high sweep rates and larger intervals at low sweep rates. This parameter adaptation allows the system to maintain optimal performance across different operating conditions while keeping the overall system structure relatively simple.
2Productivity
If high sweep rates are used to improve imaging speed, then productivity increases, but measurement precision may deteriorate due to motion-induced artifacts and reduced sampling accuracy
Solution Approach 1:
The system dynamically adjusts the optical frequency sampling interval based on the instantaneous sweep rate. During high-speed imaging, the system automatically reduces the sampling interval to capture more data points, preventing undersampling artifacts. This dynamic adjustment maintains sampling accuracy even at high sweep rates, resolving the contradiction between speed and precision by adapting the sampling strategy to current operating conditions.
Solution Approach 2:
The patent implements a feedback mechanism where the system monitors the sweep rate and uses this information to adjust the sampling interval in real-time. The swept source's actual performance feeds back to the control system, which then modifies the sampling parameters accordingly. This closed-loop control ensures that sampling accuracy is maintained across varying sweep rates, allowing high-speed imaging without sacrificing measurement precision.
3Measurement precision
If low sweep rates are used to improve sampling accuracy, then measurement precision improves, but productivity decreases due to longer imaging time
Solution Approach 1:
The patent changes the optical frequency sampling interval parameter based on the desired sweep rate and imaging requirements. When operating at low sweep rates, the system increases the sampling interval to maintain adequate sampling density without unnecessarily extending imaging time. This parameter optimization allows the system to achieve good sampling accuracy at low speeds while minimizing imaging time, resolving the contradiction between precision and productivity.
Solution Approach 2:
The system applies partial sampling action by adjusting the sampling interval to match the actual needs of each sweep rate condition. Rather than using a uniformly small sampling interval that would ensure accuracy but increase imaging time, the system uses larger intervals when appropriate (at low sweep rates) and smaller intervals only when necessary (at high sweep rates). This selective sampling approach maintains measurement precision while optimizing imaging time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables optimal performance by adjusting sampling intervals based on sweep rates, ensuring high-speed imaging with deep spatial resolution and flexibility in scan modes, overcoming the limitations of traditional systems.
Implementation Method 1
combining optical signals returning from the reference arm and the sample arm to generate an interference signal
Implementation Method 2
the k-clock module comprises an etalon that filters the swept optical signal from the optical swept source system
Implementation Method 3
a photodetector to detect the optical interference signal and generate an electrical interference signal
Data Source
AI summary
An optical coherence tomography system utilizes an optical swept source that frequency scans at least two different sweep rates. In this way, the system can perform large depth scans of the sample and then the same system can perform shorter depth high precision scans, in one specific example. In order to optimally use the analog to digital converter that samples the interference signal, the system further samples the interference signals at different optical frequency sampling intervals depending upon the selected sweep rates of the optical swept source. This allows the system to adapt to different sweep rates in an optimal fashion.